go用map实现set

package main

import (
    "fmt"
)

type Set map[string] struct{}

func (s Set) Has(key string) bool {
    _, ok := s[key]
    return ok
}

func (s Set) Add(key string) {
    s[key] = struct{}{}
}

func (s Set) Delete(key string) {
    delete(s, key)
}

func main() {
    s := make(Set)

    s.Add("Tony")
    s.Add("Tom")

    fmt.Println(s.Has("John"))
    fmt.Println(s.Has("Tony"))
}